IPG Photonics

About: IPG Photonics is a based out in . It is known for research contribution in the topics: Laser & Fiber laser. The organization has 903 authors who have published 1241 publications receiving 63339 citations.

Comparison of a novel 450-nm laser with Ho:YAG (2100 nm), Tm fiber (1940 nm), and KTP (532 nm) lasers for soft-tissue ablation

Abstract: Three lasers were directly compared, including the Ho:YAG laser (λ = 2100 nm), Tm fiber laser (λ = 1940 nm) operating in 3 different modes (CW, regular pulse, and super pulse), and blue diode laser (λ = 442 nm) for vaporization and coagulation efficiency for treating blood-rich soft tissues, ex vivo, in a porcine kidney model at quasi-contact cutting in water. In addition, experimental results were compared with published data on performance of KTP laser (λ = 532 nm) at similar experimental settings (Power = 60 W and cutting speed = 2 mm/s). Tm fiber laser in pulsed mode and blue laser produced highest vaporization rates of 3.7 and 3.4 mm3/s, respectively. Tm fiber laser (in both CW and pulsed modes) also produced the largest coagulation zone among the laser sources tested. A carbonization zone was observed for Tm fiber laser in CW and pulsed modes, as well as for the blue diode laser. Tm fiber laser in super-pulse mode and Ho:YAG laser both resulted in irregular coagulation zones without carbonization. Comparison with known data for KTP laser revealed that tissue effects of the blue laser are similar to that of the KTP laser. These results suggest that the combination of the two lasers (Tm fiber and blue diode) in one system may achieve high cutting efficiency and optimal coagulation for hemostasis during surgical treatment. Ex vivo testing of the combined system revealed feasibility of this approach. The combination of the CW Tm fiber laser (120W) and the blue diode laser (60W) emitting through a combination tip were compared with CW 120 W Tm fiber laser alone and 120 W Ho:YAG laser. Vaporization rates measured 34, 28, and 6 mm3/s, and coagulation zones measured 0.6, 1.3, and 1.7 mm, respectively. A carbonization zone was only observed with CW Tm fiber laser. The vaporization rate of combined CW Tm fiber laser / blue diode laser was comparable to published data for KTP laser for equivalent total power. Thus, high-power blue diode laser, Tm fiber laser, and their combination may provide an alternative to conventional Ho:YAG and KTP lasers for applications in urology and other surgical fields.

Multiple-beam laser processing using multiple laser beams with distinct wavelengths and/or pulse durations

Abstract: Multiple-beam laser processing may be performed on a workpiece using at least first and second laser beams with different characteristics (e.g., wavelengths and/or pulse durations). In some applications, an assist laser beam is directed at a target location on or within the workpiece to modify a property of the non-absorptive material. A process laser beam is directed at the target location and is coupled into absorption centers formed in the non-absorptive material to complete processing of the non-absorptive material. Multiple-beam laser processing may be used, for example, to drill holes in a substrate made of alumina or other transparent ceramics. In other applications, multiple-beam laser processing may be used in melting applications such as micro-welding, soldering, and forming laser fired contacts. In these applications, the assist laser beam may be used to modify a property of the material or to change the geometry of the parts.

Source mechanisms and near-source wave propagation from broadband seismograms

Abstract: Recording seismic events at teleseismic distances with broadband and high dynamic range instruments provides new high-quality data that allow us to interpret in more detail the complexity of seismic rupture as well as the heterogeneous structure of the medium surrounding the source where waves are initially propagating Wave propagation analysis is performed by ray tracing in a local cartesian coordinate system near the source and in a global spherical coordinate system when waves enter the mantle Seismograms are constructed at each station for a propagation in a 25-D medium Many phases can be included and separately analyzed; this is one of the major advantages of ray tracing compared to other wave propagation techniques We have studied four earthquakes, the 1988 Spitak Armenia Earthquake (Ms = 69), the 1990 Iran earthquake (Ms = 77), the 1990 romanian earthquake (Ms = 58) and the 1992 Erzincan, Turkey earthquake (Ms = 68) These earthquakes exhibit in different ways the complexity of the rupture and the signature of the medium surrounding the source The use of velocity seismograms, the time derivative of displacement, increases the difficulty of the fit between synthetic seismograms and real seismograms but provides clear evidence for a need of careful time delay estimations of the different converted phases We find that understanding of the seismic rupture as well as the influence of the medium surrounding the source for teleseismically recorded earthquakes requires a multi-stop procedure: starting with ground displacement seismograms, one is able to give a first description of the rupture as well as of the first-order influence of the medium Then, considering the ground velocity seismograms makes the fit more difficult to obtain but increases our sensitivity to the rupture process and early converted phases With increasing number of worldwide broadband stations, a complex rupture description is possible independently of field observations, which can be used to check the adequacy of such complicated models

Optical methods to monitor temporal changes at the seafloor: The Lucky Strike deep-sea hydrothermal vent field (Mid-Atlantic Ridge)

Abstract: Newly developed image processing techniques, including gigamosaicing, video-based 3D terrain reconstruction, and video-based fluid velocimetry have provided key information to understand the distribution, nature, and quantification of hydrothermal activity at a deep sea vent field (Lucky Strike, Mid-Atlantic Ridge). These imaging techniques have been coupled with seafloor instrumentation and sampling, allowing us to develop a comprehensive approach to study active processes in the submarine environment that can be transferred to other study areas.